Constellation allows insecure use of LUKS2 persistent storage partitions

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Constellation is the first Confidential Kubernetes. The Constellation CVM image uses LUKS2-encrypted volumes for persistent storage. When opening an encrypted storage device, the CVM uses the libcryptsetup function crypt_activate_by_passhrase. If the VM is successful in opening the partition with the disk encryption key, it treats the volume as confidential. However, due to the unsafe handling of null keyslot algorithms in the cryptsetup 2.8.1, it is possible that the opened volume is not encrypted at all. Cryptsetup prior to version 2.8.1 does not report an error when processing LUKS2-formatted disks that use the cipher_null-ecb algorithm in the keyslot encryption field. This vulnerability is fixed in 2.24.0.

Source published

27 Oct 2025 19:33:23 UTC

Source modified

28 Nov 2025 14:45:46 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 8.3 CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Constellation is the first Confidential Kubernetes. The Constellation CVM image uses LUKS2-encrypted volumes for persistent storage. When opening an encrypted storage device, the CVM uses the libcryptsetup function crypt_activate_by_passhrase. If the VM is successful in opening the partition with the disk encryption key, it treats the volume as confidential. However, due to the unsafe handling of null keyslot algorithms in the cryptsetup 2.8.1, it is possible that the opened volume is not encrypted at all. Cryptsetup prior to version 2.8.1 does not report an error when processing LUKS2-formatted disks that use the cipher_null-ecb algorithm in the keyslot encryption field. This vulnerability is fixed in 2.24.0.

Source published

Oct 27, 2025, 7:33:23 PM (timezone not stated)

Source modified

Nov 28, 2025, 2:45:46 PM (timezone not stated)

Observed here

11 Nov 2026 03:36:46 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 8.3 CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Constellation is the first Confidential Kubernetes. The Constellation CVM image uses LUKS2-encrypted volumes for persistent storage. When opening an encrypted storage device, the CVM uses the libcryptsetup function crypt_activate_by_passhrase. If the VM is successful in opening the partition with the disk encryption key, it treats the volume as confidential. However, due to the unsafe handling of null keyslot algorithms in the cryptsetup 2.8.1, it is possible that the opened volume is not encrypted at all. Cryptsetup prior to version 2.8.1 does not report an error when processing LUKS2-formatted disks that use the cipher_null-ecb algorithm in the keyslot encryption field. This vulnerability is fixed in 2.24.0.

Source published

27 Oct 2025 20:15:53 UTC

Source modified

8 Oct 2026 11:10:00 UTC

Observed here

25 Oct 2026 03:17:18 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 8.3 CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

### Summary A malicious host may provide a crafted LUKS2 volume to a confidential computing guest that is using the [OpenCryptDevice](https://github.com/edgelesssys/constellation/blob/6eff250f16f8ae48221d412550e4a64a4bf0d77b/csi/cryptmapper/cryptmapper.go#L89) feature. The guest will open the volume and write secret data using a volume key known to the attacker. The attacker can also pre-load data on the device, which could potentially compromise guest execution. LUKS2 volume metadata is not authenticated and supports null key-encryption algorithms, allowing an attacker to create a volume such that the volume: - Opens (cryptsetup open) without error using any passphrase or token - Records all writes in plaintext (or ciphertext with an attacker-known key) - Contains arbitrary data chosen by the attacker ### Details The Constellation CVM image uses LUKS2-encrypted volumes for persistent storage. When opening an encrypted storage device, the CVM uses the `libcryptsetup` function [crypt_activate_by_passhrase](https://github.com/martinjungblut/go-cryptsetup/blob/fd0874fd07a6e477f0a4d18f2e80234983afe74f/device.go#L261). If the VM is successful in opening the partition with the disk encryption key, it treats the volume as confidential. However, due to the unsafe handling of null keyslot algorithms in the cryptsetup 2.8.1, it is possible that the opened volume is not encrypted at all. Cryptsetup prior to version 2.8.1 does not report an error when processing LUKS2-formatted disks that use the `cipher_null-ecb` algorithm in the keyslot `encryption` field. ### Impact A LUKS2 disk encrypted with a master key, which is in turn encrypted with user passwords stored in some number of keyslots. By creating a malicious disk which sets the keyslot encryption algorithm to `”crypto_null-ecb”`, an attacker can construct a disk such that keyslot decryption does not depend in any way on the enclave-held secret data. When a confidential guest opens such a device using `cryptsetup open`, the mapped disk is created without error, and any further writes to the disk are encrypted using an attacker-controlled key. ### Patches To protect against this and similar attacks, Constellation now performs detached reading of LUKS headers. The header is copied into the encrypted memory of the CVM and then verified. The verified header is then used to open the encrypted LUKS device in detached header mode. This was implemented in https://github.com/edgelesssys/constellation/pull/3927 and release as part of [Constellation v2.24.0](https://github.com/edgelesssys/constellation/releases/tag/v2.24.0).

Source published

27 Oct 2025 16:20:25 UTC

Source modified

1 Dec 2025 16:21:13 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Publisher rating · HIGH

Constellation has insecure LUKS2 persistent storage partitions which may be opened and used in github.com/edgelesssys/constellation

Source published

30 Oct 2025 15:02:33 UTC

Source modified

3 Mar 2026 04:57:05 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.